Design And Pavement Performance Of Ultra-thin Snow Melt Salt Asphalt Mixture Pavement Overlay

In winter, roads are covered with heavy snow and ice so their skid-resistance decline rapidly. It has a great effect on traffic safety and road service level. The appearance of snow melt salt asphalt mixture provides a new idea to remove snow and ice. But this technology is mainly applied to full depth pavement structure of new project. To overhaul and intermediate maintenance, it will increase the road weight and grade elevation. What’s more, the salty material of the lower pavement cannot be released in the snow. In that condition, the intended effect won’t be reached, project cost will be raised and materials will be wasted. So it is of great practical significance to design ultra-thin snow melt salt asphalt mixture which has good snow melt effect and low price.Firstly, using progressively filling trials, taking coarse aggregate clearance rate(VCA), CBR, and maximum carrying capacity(MPL) as the main indicators, the mineral aggregate composition of ultra-thin SMA-5 mixture was researched. The best ratio of each shift aggregate and the key sieve of coarse and fine aggregate were obtained. The best aggregate thickness ratio was got by Marshall Test, which optimized the SMA-5 mixture gradation range. Then taking advantage of dynamic shear rheometer(DSR) and a Brookfield viscometer, dynamic rheological characteristics of high viscosity modified asphalt mortar was researched and suitable rubber powder ratio range was recommended. And in the premise of the best powder ratio, the impact on asphalt mortar characteristics of alternative slag ratio was studied. Simulating ultra-thin overlay’s actual service condition, improvement effect on ordinary mixture’s performance of the adding of ultra-thin snow melt salt asphalt mixture(TSSAM) was researched. Then the amount of salt substitute’s impact on the mixture’s high temperature stability, low temperature cracking resistance, water stability and adhesion were analyzed. Combined with mortar and asphalt mixture test’s results, the maximum amount of salt alternative was got. Finally, according to freezing point depression theory, evaluation index of TSSAM’ snowmelt performance and lifetime was put forward and the study on snowmelt performance and lifetime was conducted.In this paper, TSSAM’ basic material composition and key design parameters were obtained from three aspects as following: the composition of aggregate gradation, asphalt mortar properties and asphalt mixtures pavement performance. Then their snowmelt performance and lifetime under different conditions were verified, which would provide a theoretical basis for the design and construction of TSSAM.